This invention relates to the art of electrostatographic copying, an electrostatographic photosensitive device and more particularly to a method for the preparation of such a device. The art of electrostatograhic copying, originally disclosed by C. F. Carlson in U.S. Pat. No. 2,297,691, involves as an initial step, the uniform charging of a plate comprised of a conductive substrate normally bearing on its surface a non-conductive barrier layer which is covered by a photoconductive insulating material. This is followed by exposing the plate to activating radiation in imagewise configuration which results in dissipation of the electrostatic charge in the exposed areas while the non-exposed areas retain the charge in a pattern known as the latent image. The latent image is developed by contacting it with an electroscopic marking material commonly referred to as toner. This material is electrostatically attracted to the latent image which is, by definition, in the configuration of those portions of the photoreceptor which were not exposed to the activating radiation. The toner image may be subsequently transferred to paper and fused to it to form a permanent copy. Following this, the latent image is erased by discharging the plate and excess toner cleaned from it to prepare the plate for the next cycle. Typically, the photosensitive plate is in the form of a cylindrical drum generally referred to as the photoreceptor.
The advent of high speed electrostatographic copier/duplicators has lead to the desirability of using endless belts as the photosensitive element. Such belts exhibit the requisite flexibility which enhances their adaptability to high speed copier/duplicators. Suitable belts generally are quite thin and have a surface with a high degree of smoothness due to the need for the production of high quality images on the image retention side of the belt. A further requirement is that the belt have a relatively high tensile strength. Satisfactory belts can be prepared by electroplating a ductile metal, e.g. stainless steel, brass, aluminum or nickel onto a mandrel to form a thin, uniform layer of the metal. Removal of the metal layer from the mandrel provides the substrate upon which the photoconductive material can be deposited to form the xerographic belt. While this electroforming method of preparing the belt substrate has proven quite satisfactory, alternative, less expensive methods would be desirable. One method which has been considered as an alternative involves the use of a thin film of an organic resin as the substrate material. Deposition of a conductive material onto the organic film with the subsequent application of a layer of photoconductive material would provide the necessary multi-layered belt. However, heat treatments are typically necessary to treat the photoconductive material and/or the conductive layer which tend to adversely affect the organic film substrate. This is the case because organic resin films are typically rather heat sensitive and any thermally induced shriveling of the film will disrupt the necessary uniformity of the belt's surface.
It would be desirable and it is an object of the present invention to provide a novel method for the preparation of an endless belt electrostatographic photosensitive device which employs an organic film as the substrate.
A further object is to provide such a method which eliminates the problems associated with the inability of the organic film to withstand the temperatures the belt must be subjected to in treating the photoconductive and/or conductive layer.